Automobiles, especially passenger cars, are usually provided with a cigarette lighter for example on the dashboard. The cigarette lighter is an electric device which receives electrical energy from the automobile electricity system and provides a high temperature thermal output. To provide electricity to the cigarette lighter, the automobile dashboard is provided with a cigarette lighter holder which is in electrical connection with the automobile electricity system. The holder is in the form of a blind bore defining a positive contact and a negative contact respectively at the bottom and the side thereof, while the cigarette lighter is a plug-like member having a positive contact and a negative contact defined at the front tip and the side thereof to be in engagement with the corresponding contacts of the holder so as to establish electrical connection therebetween. Since the cigarette lighter holder is in electrical connection with the automobile electricity system, it is also used as a power outlet of the automobile electricity system to which electrical or electronic appliances may be attached.
Currently, there are two different specifications of the cigarette lighter holder adapted in cars from different manufacturers, of which the inside diameter of the bore is 20 mm and 22 mm respectively. Due to the difference in the specifications of the cigarette lighter holders, adaptors of two different specifications are needed in order to match these different specification cigarette lighter holders. This not only increases the cost of wholesale inventory, but is also troublesome in identifying the specific specification of the cigarette lighter holder.
Furthermore, since the connection between the cigarette lighter holder and an electrical or electronic appliance is provided by the simple insertion of a plug-like adaptor into the bore of the cigarette lighter holder, disengagement of the adaptor from the cigarette lighter holder may occur by being accidentally impacted or pulled, especially when vibration or shock occurs during the operation of the automobile.
One of the most commonly used electronic appliances that is powered via the cigarette lighter holder is a mobile phone which, usually, has to be held by hand in communication operation. This is very dangerous for a driver has to use one hand to hold the phone and control the steering wheel with only the other hand. Traffic accidents may thus occur. To overcome such a problem, mobile phone holders for holding the mobile phone inside a car and allowing ready operation without hand holding the phone are available in the market. These currently-available mobile phone holders are usually fixed to for example the dashboard of the car by means of adhesive pads or screws which damage the dashboard aesthetically once the holder is removed.
Thus it is desirable to have an extension device for mounting to a cigarette lighter holder which not only allows a secure engagement with the cigarette lighter holder, but also provides an end holder for holding thereon for example a mobile phone to allow a driver to use the mobile phone without hand holding the phone.